The long-term objective of the research outlined in this proposal is to establish stable and immortalized parotid and submandibular cell lines which will pave the way for future studies of the molecular regulation of salivary-specific gene expression and the electrophysiology of salivary secretion. Specific aims of this proposal include: (1) to generate and characterize transgenic mice lines with chimeric construct, pR15-PyLT, which harbors polyomaviral large T antigen under the control of 5'-flanking region of rat salivary-specific PRP gene, R15, and (2) to establish and characterize differentiated parotid and submandibular cell lines from R15- PyLT transgenic lines. Our hypothesis predicts that (a) the specific expression of polyomaviral large T antigen in the salivary gland will lead to immortalizing primary salivary cells in culture, and allowing their growth without crisis or senescence, and (b) the expression of large T antigen may have no effect on cell differentiation in the transgenic mice as reported previously. Collectively, cultures of differentiated salivary cells derived from transgenic mice may proliferate extensively in vitro, whereas salivary cells without immortalizing or transforming genes did not. This property will allow us to establish immortalized salivary cell lines conferred by the expression of PyLT. Salivary glands produce secretion that bathe and protect the oral cavity. The availability of immortalized salivary cell lines which resemble their parental cells in most differentiation characteristics would clearly facilitate the studies which may finally lead to clinical treatment for patients who are orally compromised because of periodontal disease, Sjorgen's syndrome, and HIV disease. Knowledge from transgenic salivary-specific gene expression is also of practical importance in implementing genetic engineering and possibly gene therapy for individuals who suffered from Xerostomia caused by salivary dysfunction.